Safety device



H. A. BUKER SAFETY DEVICE Oct. 29, 1963 2 Sheets-Sheet 1 Filed Aug. 24. 1961 W WM m m m a Gm MN Nu United States Patent 3,108,491 SAFETY DEVICE Harvey A. hither, West Lafayette, Ohio, assignor to The Jones Metal Products Company, West Lafayette, (lino, a corporation of Ohio Filed Aug. 24, 1961, Ser. No. 133,704 11 Claims. (Cl. 74-5l5) This invention relates in general to safety devices, and more particularly to a fluid actuated, pull-back device, for protecting the hands of a workman operating power machinery, such as a stamping press or like type of machine.

Safety pull-back devices for press operators are known in the art. However, in these prior art arrangements, the device generally comprises a mechanical linkage coacting directly between the press ram and the hand harness for the press operator, so that as the press head or press ram is lowered, the linkage transmits a pull to the harness, thereby automatically pulling the operators hands from under the pres head area.

These prior 'art devices have not been altogether satisfactory in that while the hands of the operator might be sufficiently withdrawn from under the press head, the harness generally prevents any substantial movement of the operators hands in the closed position of the press, thus greatly restricting the movement and activity of the operator, and materially decreasing the efliciency of the operation.

The present arrangement provides a pull-back device which is fluid actuated, and which can be readily attached to existing presses, or which can be easily embodied in new presses, and which is effective to automatically withdraw the hands of the operator from the press head area upon actuation of the press, and which provides for much greater freedom of movement of the hands of the operator when shackled in the harness of the mechanism, resulting in much greater efiiciency for the operation.

Accordingly, an object of the invention is to provide a novel pull-back safety device for use by workmen operat ng power machinery.

Another object of the invention is to provide a safety device of the latter mentioned type which may be readily mounted or attached to existing presses and/ or embodied in new presses, and which can be adjusted to vary the timing of the pull of the device.

Another object of the invention is to provide a pullback or pull-out safety device of the above mentioned type wherein the device can be readily adjusted for different sizes of operators, and which when not in use is adapted for convenient movement out of the way of the immediate area adjacent to the associated press.

A still further object of the invention is to provide a safety pull-back or pull-out device of the above type, including a trip cam adapted for mounting on a movable press head of a press, a three-way fluid or air valve adapted to be actuated by the trip cam, and operatively connected to a pilot valve controlled, double acting air motor unit, which in turn actuates the hand harness mechanism, for pulling of the operators hands out of the press head area, upon actuation of the three-way valve by said trip cam, but which automatically releases upon predetermined closure of the press.

Other objects and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic illustration of a press having the pull-out safety device of the invention embodied there- With;

FIG. 2 is an enlarged, fragmentary, broken view illustrating the various parts of the mechanism, including the air control valve and the trip cam, the pilot actuated motor unit which actuates the hand harness mechanism, and the mechanism for guiding and controlling the hand harness pull cables; in dot-dash lines there is illustrated an inactive position of the tubular guide member of the device when moved upwardly to inactive position;

FIG. 3 is a partially sectioned, elevational View of the pilot valve for controlling the directional valve associated with the reciprocal motor unit;

FIG. 4 is a fragmentary, diagrammatical illustration of the latter mentioned directional valve and its connection to the reciprocal motor unit.

Referring new again to the drawings, 10 designates a power machine, which in the arrangement illustrated is a press, having the safety pull-out mechanism of the invention embodied therewith.

The safety pull-out device broadly comprises a trip cam 12 mounted on the movable part or head 13 of the press, an air control valve 14 actuated by means of roller mechanism 15 and mounted stationary with respect to the press frame, a double-acting, pilot valve controlled, air actuated motor unit 16 mounted adjacent the press, with the piston rod 16a of the motor unit being connected to a rod-like member 18 mounted for lengthwise movement, and with the rod-like member 18 being attached to a pull cable 22 which extends through tubular guide mechanism and is connected to the hand straps or harness 26, which are adapted to be attached to the operators hands.

The aforementioned trip cam 12 is preferably adjustably mounted on a slotted (as at 31) plate or frame 36 and as by means of threaded fastener elements and associated plate 32, so that the cam position can be adjusted with respect to the press head, and thus time the pull of the mechanism.

The cam 12 comprises a leading tapered surface 34 and a generally vertical upper actuating surface 34a, the latter surfaces being adapted for coaction with roller 36 secured to pivotal finger 38 mounted on bracket 38a which may be mounted on the press frame. Roller 36 and finger 38 preferably have spring means, such as a torsion spring 39 associated therewith so that swinging movement of the roller about pivotal axis 39a of the finger 38, due to engagement between the roller 36 and cam 12, is resiliently opposed by spring 39. Finger 3-8 is adapted for coaction with spring loaded plunger 40 of conventional threeway valve 14, to automatically actuate the slide element of the valve 14 upon contact between the roller 36 and the trip cam 12. A suitable control valve for such operation has been found to be a Bellows RCV-1/8 valve manufactored by the Bellows Company of Akron, Ohio. Upon actuation of the valve 14 due to coaction between the trip cam 12 and the roller 36 and consequent pivoting of finger 38, the air pressure entering the valve, as at 42, is directed through line 43 to a pilot valve 44 mounted on the double-acting piston type air motor unit '16, which may be secured to a side of the press frame.

Pilot valve 44 comprises a piston 46 (FIG. 3) slidable in chamber 56a, with a stem 47, attached as at 47a, to the piston 46. A lower or half piston 48 slidable in chamber 49 is also provided for a reason to be hereinafter dis cussed.

A distributing valve 50 is attached to the pilot valve 44, for controlling the direction of application of pressurized air, entering as at 52a, to the reciprocal motor unit 16. Valve 50 includes valve slide 52, operating in chamber 54, and coupled to stem 47 of the pilot valve. Spring 56 may be provided for resiliently urging slide 52 against the valve seat 56a.

Referring now in particular to FIGS. 3 and 4, when air pressure is applied via line 43 tothe piston 46 of the pilot valve, thus moving the stem 47 downwardly (with reference to FIG. 3) the slide 52 is moved from its full line position as shown in FIG. 4, to the phantom line position, thereby opening distributing port 58, and closing distributing port 6% from communication with pressurized air in chamber 54. Upon opening of port 58, pressurized air coming into chamber 54 at entry port 5211, passes via port 58 into the rearward end of reciprocal motor unit 16 and drives the piston and associated piston rod 16a outwardly, while air from the forward end of the motor unit is exhausted via distributing port 69 and exhaust port 62, and as illustrated by the arrows in FIG. 4.

When the trip cam 12 on press head 13 has moved past roller 36, spring 39 causes clockwise (as viewed in FIG. 2) pivoting of finger 38, thereby permitting outward movement of spring loaded plunger 40 of valve 14 which activates the valve slide to cause isolation of fiuid pressure line 43 from the air pressure entering valve 14 at 42, and causes venting of line 4-3 to atmosphere. Thereupon the air pressure entering chamber 49 from inlet port 52a of valve mechanism 50 moves piston 48 and associated piston 46 upwardly, thereby causing slide 52 to move back to the full line position illustrated in FIG. 4. In the latter position, air pressure in chamber 54 passes via port 69 to the left hand chamber of motor unit 16 while fluid is vented via port 53 and exhaust port 63, from the right hand chamber of motor unit 16, thereby causing retraction of piston rod 16a. It will be seen therefore that as soon as the cam 12 moves past roller 36, that the hands of the workmen are no longer restrained in held-back position, thus greatly increasing the efficiency and mobility of the operator. Adjustable metering pins or valves 64, which in the embodiment illustrated are threaded into exhaust ports 62 and 63, are provided for selectively changing the speed of reciprocation of the motor unit 16, thereby providing for selective adjustment of the speed of pull-back.

The piston rod 16a of the motor unit 16 is connected by linkage 65 to the aforementioned plunger rod 18 which is mounted in a sleeve-like carrier or support 66, attached to the press frame. The carrier 66 at its rearward end communicates with a block-like head portion 67, including an L-shaped guide portion 67a. Pivoted as at 68 to the head portion 67 is a further block portion 69 which in turn has associated therewith a tubular portion 70, which at its outer end is curved as at 70a.

The aforementioned pull wire 22 is connected as at 72 to the rod 18, and passes through the head 67 and the associated tubular member 70 mounted on block 69. Such wire extends out of the curved portion 70a of the tubular member 7 t) and is connected to a coupling and adjusting block '74-. Flexible and preferably plastic covered pull cables 76 for the hand or wrist harness 26 are adjustably attached to the coupling member 74 as by means of threaded fasteners 84). By adjustment of the effective length of the flexible pull cables 76, and as by means of fasteners 80, the device can be readily adjusted for different sizes or lengths of arms of operators.

As illustrated in dot-dash lines in FIG. 2 when the device is not in use, the block member 69 and associated tubular member 70 can be pivoted upwardly to inactive position, and thus out of interfering or projecting relation with aisleways along the press. A spring loaded plunger mechanism 82 may be provided on mount 67a, which is adapted for locking coaction with opening 84 in pivotal block portion 69, and which may be utilized to hold the lock portion 69 in upwardly swung or inactive position, by abutting coaction of the plunger with the forward surface of block portion 69.

From the foregoing discussion and accompanying drawings it will be seen that the invention provides a novel fluid actuated pull-back safety device, and one wherein the timing of the pull-back can be adjusted, the speed of the pull-back can be adjusted, and wherein the device may be effectively adjusted for use with different sizes of operators arms, and also a device wherein the operator has substantially free movement of his hands immediately upon closure of the press, thereby providing a more convenient and efliciently operating arrangement for a press operator.

The terms and expressions which have been used are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of any of the features shown or described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

I claim:

1. In a pull-back safety device for power machinery including a ram, such as a press, comprising a fluid powered motor unit, means coupled to said motor unit and adapted for coupling to harness means for pulling back a machine operators arms, and trip and valve means for actuating said motor unit during the operative stroke of the ram to first cause the pulling back of the machine operators arms during a predetermined portion of the rams operative stroke and then to subsequently cause actuation of said motor unit to release such pulling back of the machine operators arms during the final portion of the rarns operative stroke.

2. In a pull-back safety device for power machinery including a ram, such as a press, comprising trip means, valve means for directing pressurized fluid flow, said valve means being adapted for automatic actuation by said trip means coincident with the operative stroke of the ram, a fluid pressure actuated reciprocal motor unit, other valve means for controlling the actuation of said motor unit, said other valve means being adapted for actuation by the first mentioned valve means during the operative stroke of the ram, and harness mechanism operatively connected to said motor unit for pulling back a machine operators arms upon predetermined actuation of said motor unit, said means being operative during the operative stroke of the ram to first cause the pulling back of the machine operators arms during a predetermined portion of the rams operative stroke, and then subsequently to cause reverse actuation of said motor unit to release such pulling back of the machine operators arms during the final portion of the rams operative stroke.

3. In a pull-back safety device in accordance with claim 2, wherein said trip means comprises a trip cam adapted for mounting on the movable ram of the press, roller means adapted for mounting on the press frame for engagement with said trip cam, a finger adapted for pivotal mounting on the press frame, means operatively connecting said roller to said finger whereby said finger is caused to pivot upon engagement of said roller with said trip cam, and means resiliently opposing pivotal movement of said finger, said finger being operable to actuate said first mentioned valve means.

4. In a pull-back safety device in accordance with claim 3, including means for adjustably mounting said cam on the ram, for varying the position of said cam with respect to the ram, whereby the timing of the pull-back and release can be selectively varied.

5. In a pull-back safety device in accordance with claim 2, wherein said other valve means includes fluid control means for selectively varying the speed of actuation of said motor unit to thereby change the speed of reciprocation thereof.

6. In a pull-back safety device in accordance with claim 2, wherein said harness mechanism includes end straps and flexible elements connected to said straps, and means for selectively adjusting the length of the flexible elements.

7. In a pull-back safety device in accordance with claim 2, including means operatively coupling said motor unit to said harness mechanism, said last mentioned coupling means comprising a reciprocal rod coupled to said motor unit for reciprocation therewith, a housing member,

an elongated generally flexible element movable lengthwise in said housing member and being coupled to said rod and to said harness mechanism, said housing member at one end thereof comprising a curved portion, and means pivotally mounting said curved portion whereby the latter can be swung upwardly to an inactive position.

8. In a pull-back device in accordance with claim 7, including means for locking said housing portion in predetermined position.

9. In a pull-back safety device for a reciprocal press including a ram, such as a stamping press comprising, trip means mounted on the movable ram of the press, first valve means mounted on the press frame for directing pressurized fluid flow and adapted for actuation by said trip means during a predetermined portion of the rams operative stroke, a reciprocal double acting air actuated motor unit, second valve means operatively coupled to said first valve means for controlling the direction of actuation of said motor unit, harness mechanism for attachment to the arms of a press operator, and coupling mechanism operatively connecting the motor unit to said harness mechanism, said harness mechanism being actuated to withdraw the operators arms from the vicinity of the ram on predetermined actuation of said motor unit, said first and second valve means being operable during the operative stroke of said ram to first cause the pulling back of the operators arms during coaction between said trip means and said first valve means, and then upon passing of said first valve means by said trip means to cause actuation of said motor unit in the opposite direction to completely release such pulling back of the operators arms during the final portion of the rams operative stroke.

10. In a pull-back safety device for a press including a reciprocal ram, comprising a reciprocal, double acting fluid actuated motor unit, trip means adapted for mounting on the movable ram of the press, valve means for directing pressurized fluid flow and adapted for actuation by said trip means during the operative stroke of the ram, said valve means including a control valve for directing pressurized fluid, a pilot valve operatively coupled to said control valve for actuation of the pilot valve, a directional valve operatively coupled to said pilot valve for actuation of said directional valve, said directional valve being adapted for coupling to a source of pressurized fluid for applying pressun'z/ed fluid to said motor unit, said trip means actuating said pilot valve via said control valve after expiration of a predetermined portion of the rams operative stroke, whereby said motor unit is caused to move outwardly, harness means adapted for coupling to a press operator, and means coupling said harness means to said motor unit for movement therewith, said pilot valve being operable to be actuated by the fluid pressure from said source when said trip means passes said control valve and becomes inactive during the final portion of the rams operative stroke, whereby said directional valve is actuated to cause retraction of said motor unit and complete release of the pull back on such harness means.

11. A pull-back safety device in accordance with claim 10, including means for selectively adjusting the position of said trip means with respect to the ram of the press, for varying the timing of the actuation of said motor unit in response to the operative stroke of the ram.

References Cited in the file of this patent UNITED STATES PATENTS 2,339,214 Yanchenko Jan. 11, 1944 2,427,928 Shaw Sept. 23, 1947 2,429,065 Korkowski Oct. 14, 1947 2,642,755 Shaw June 23, 1953 FOREIGN PATENTS 425,982 Germany Mar. 2, 1926 

1. IN A PULL-BACK SAFETY DEVICE FOR POWER MACHINERY INCLUDING A RAM, SUCH AS A PRESS, COMPRISING A FLUID POWERED MOTOR UNIT, MEANS COUPLED TO SAID MOTOR UNIT AND ADAPTED FOR COUPLING TO HARNESS MEANS FOR PULLING BACK A MACHINE OPERATOR''S ARMS, AND TRIP AND VALVE MEANS FOR ACTUATING SAID MOTOR UNIT DURING THE OPERATIVE STROKE OF THE RAM TO FIRST CAUSE THE PULLING BACK OF THE MACHINE OPERATOR''S ARMS DURING A PREDETERMINED PORTION OF THE RAM''S OPERATIVE STROKE AND THEN TO SUBSEQUENTLY CAUSE ACTUATION OF SAID MOTOR UNIT TO RELEASE SUCH PULLING BACK OF THE MACHINE OPERATOR''S ARMS DURING THE FINAL PORTION OF THE RAM''S OPERATIVE STROKE. 